The H1N1 spread

You know how I like numbers, right? I like graphs too.

While looking up information for my last influenza A (H1N1) post, I came across the H1N1 situation updates WHO releases twice daily. It includes confirmed information about the spread of the disease: the number of countries in which the virus is present, the number of cases, and the number of deaths.

Five days ago I wrote, “there have been 898 confirmed cases of this flu with 20 deaths.” Currently, there are more than 2½ times as many confirmed cases and just over twice as many deaths.

I thought it would be interesting to the figures from the updates and see how they map out over time. Here’s a graph of the number of worldwide confirmed cases of the influenza A (H1N1) virus, by date:

A few things to note:

• The dates seem spread out at the beginning. This is because on May 1, they doubled the release rate of updates to two each day. To maintain a linear graph, I duplicated the daily release data in April to also show two numbers for each day.
• At times, reported cases are held pending confirmation. When confirmed, the numbers jump suddenly after an apparent plateau. This is an artefact of the reporting process, not a reflection of the way the disease spreads.

Based on the reported figures, the mortality rate has been dropping. It was 10% on April 27 and is 1.9% today. This is likely do to the spread of the disease outside of Mexico, where it seems to be far less lethal.

Although the symptoms are generally mild, there’s no arguing that the infection rate is steadily increasing.